1. Field of the Invention
The present invention relates to a laminated heat resistant alloy plate which is used for cooling a combuster of a gas turbine or a jet engine and the like.
2. Description of the Related Art
FIG. 1 shows an example of a laminated heat resistant alloy plate which is used for cooling a combustion basket or a transition piece of a combustor of a gas turbine or a jet engine and the like. In the figure, on an upper face of a fin portion of a heat resistant alloy plate 1 in which striae A are formed and cooling holes B are bored, a heat resistant alloy plate 2 in which only cooling holes C are bored and made of a material the same as or different from that of the heat resistant alloy plate 1 is brazed with nickel braze (not shown). In the laminated heat resistant alloy plate having this structure, cooling air cools the heat resistant alloy plates 1 and 2 when it enters in the striae A through the cooling holes C and is sent to the interior of the combustor through the cooling holes B. Furthermore, FIG. 2 is an enlarged view of a part of a side cross section of FIG. 1. By employing this laminated heat resistant alloy plate for a member of the combustion basket or the transition piece of the combustor, these members can be efficiently cooled by a small quantity of cooling air.
The laminated heat resistant alloy plate as described above is manufactured through the following processes: (1) forming the striae on a Ni alloy plate having appropriate thickness by a cutter having predetermined width, (2) superimposing this striated plate on a plate which is made of a material the same as or different from that of the striated plate with the Ni solder and setting them at a predetermined position so as to face the striae downward, (3) adding a load of 30 g/cm2 or more on the striated plate uniformly by dividing the load using small blocks which respectively have loading areas of 15 cm2 and less; and (4) performing a heat treatment at 1000±20° C. for 5 to 60 minutes, (5) performing a heat treatment at 1050 to 1150° C. for 15 to 60 minutes, and (6) performing a heat treatment at 1060 to 1140° C. for 2 hours or more, in an inert gas atmosphere or vacuum (See Japanese Patent Application, Second Publication, No. Hei 6-67551).
Conventionally, the maximum size of a laminated heat resistant alloy plate which is required for use for a combustor of a gas turbine is, for example, about 300 mm×300 mm, and in the case of brazing the laminated heat resistant alloy plate whose size is about 300 mm×300 mm, brazing with sufficient strength can be performed by means of the above loading condition and heat treatments under the conditions of heating temperature and time in the inert gas or vacuum. However, demand for the laminated heat resistant alloy plate whose size is about 400 mm×400 mm or more has increased in recent years as a result of increase in areas which require cooling in the combustor of the gas turbine in accordance with increases in the inlet temperature of the gas turbine. If this size of laminated heat resistant alloy plate is manufactured by the above conventional method, the strength of a brazed portion thereof may become sufficient and exfoliation may occur in the brazed portion.
Furthermore, a sheet shaped solid which is composed of a mixture of powder of Ni braze “BNi—2” based on Japanese Industrial Standard, JIS Z 3265, and acrylic resins as a binder with a ratio of 10:1 by weight is conventionally used as the braze. However, in this braze, it is difficult to maintain uniform thickness of the sheet, and internal defects due to the gas generated by the heat treatment may easily remain. Therefore, even when a laminated heat resistant alloy plate of a size of about 300 mm×300 mm is manufactured, the exfoliation may occur unless the load of 30 g/cm2 or more on the plate is divided with small areas of 15 cm2 and less.